One of the most popular over-the-counter painkillers in the UK can heighten the chances of suffering a potentially fatal cardiac arrest, a study has shown.
Researchers in Denmark found that taking ibuprofen was associated with a 31% increased risk of the emergency condition, which occurs when the heart suddenly stops pumping blood.
Other medicines from the same family of painkillers, known as non-steroidal anti-inflammatory drugs (NSAIDs), posed a similar danger, according to the findings.
They included diclofenac, which raised the risk by 50%, and was available over the counter in the UK until 2015. Today, it can only be obtained on prescription.
Heart expert Professor Gunnar Gislason, who led the study, called for tighter controls on NSAIDs.
He said: "Allowing these drugs to be purchased without a prescription, and without any advice or restrictions, sends a message to the public that they must be safe.
"The findings are a stark reminder that NSAIDs are not harmless.
"Diclofenac and ibuprofen, both commonly used drugs, were associated with significantly increased risk of cardiac arrest.
"NSAIDs should be used with caution and for a valid indication. They should probably be avoided in patients with cardiovascular disease or many cardiovascular risk factors.
"I don't think these drugs should be sold in supermarkets or petrol stations where there is no professional advice on how to use them.
"Over-the-counter NSAIDs should only be available at pharmacies, in limited quantities and in low doses."
"The current message being sent to the public about NSAIDs is wrong.
"If you can buy these drugs in a convenience store then you probably think 'they must be safe for me'.
"Our study adds to the evidence about the adverse cardiovascular effects of NSAIDs and confirms that they should be taken seriously and used only after consulting a healthcare professional."
The most common cause of a cardiac arrest is a life-threatening abnormal heart rhythm called ventricular fibrillation (VF).
It causes electrical activity in the heart to become so chaotic that the organ ceases to pump rhythmically and quivers or "fibrillates" instead. Without immediate treatment to keep the circulation going, death occurs in minutes.
Sales of over-the-counter painkillers amounted to almost £600 million in the UK in 2015, according to The Pharmaceutical Journal.
The Danish investigators studied data on all patients who had an out-of-hospital cardiac arrest in the country between 2001 and 2010.
Information on NSAID prescriptions since 1995 was obtained from pharmacies. Over-the-counter purchases of ibuprofen, the only NSAID available in Denmark without prescription, could not be included in the analysis.
For every patient, use of NSAIDs during the month before a cardiac arrest was compared with use in the 30 days leading up to that point.
Comparing the two periods for each individual eliminated the chances of chronic conditions swaying the end result.
In the 10-year period, 28,947 patients had an out-of-hospital cardiac arrest. Of these, 3,376 had been treated with an NSAID up to a month beforehand.
Use of any NSAID raised the likelihood of cardiac arrest by 31%, the scientists reported in the European Heart Journal - Cardiovascular Pharmacotherapy.
Ibuprofen and diclofenac, the two most commonly used NSAIDs, were associated with an increased risk of 31% and 50% respectively.
Three other NSAIDs, naproxen, celecoxib and rofecoxib, produced no statistically significant increase in risk, possibly because of a low sample size.
The drugs exert numerous effects on the cardiovascular system, such as influencing platelet aggregation and the formation of blood clots, that could help explain the findings, said the researchers.
The drugs may also cause arteries to constrict, increase fluid retention and raise blood pressure.
Prof Gislason, from Copenhagen University Hospital, warned people not to take more than 1,200 mg of ibuprofen in one day.
He added: "Diclofenac is the riskiest NSAID and should be avoided by patients with cardiovascular disease and the general population.
"Safer drugs are available that have similar painkilling effects so there is no reason to use diclofenac."
Dr Mike Knapton, associate medical director of the British Heart Foundation, said: "The most important point to take away from this study is to discuss all possible treatment options with your doctor, as well as the pros and cons of certain drugs, before you start taking any new medication.
"Although not all NSAIDs were found to be associated with increased risk of cardiac arrest, discussion with your doctor is imperative to make informed choice about the best treatment for you.
"For patients currently taking NSAIDs, including ibuprofen and diclofenac, the risks need to be reviewed and your specialist or GP will be able to advise on potential alternative treatments."
Copyright (c) Press Association Ltd. 2017, All Rights Reserved. Picture (c) Lauren Hurley / PA Wire.